EPA Studies Permeable Surfaces at Experimental Stormwater Parking Lot

EDISON, New Jersey, October 30, 2009 (ENS) – Polluted runoff from hard surfaces such as parking lots remains a complicated problem, but the U.S. Environmental Protection Agency is renewing its quest for solutions.

On Wednesday, the agency announced a study that will investigate ways to reduce pollution that can run off paved surfaces and improve how water filters back into the ground.

EPA is testing permeable pavement materials and rain gardens in the parking lot at the agency’s Edison, New Jersey facility, which houses offices and its laboratory.

“Runoff from parking lots and driveways is a significant source of water pollution in the United States and puts undo stress on our water infrastructure, especially in densely-populated urban areas,” said EPA Acting Regional Administrator George Pavlou.

“By evaluating different designs and materials, this study will help us develop strategies to lessen the environmental impacts of parking lots across the country and make our communities more sustainable,” he said.

This summer, EPA replaced a 43,000-square-foot section of the parking lot at Edison with three types of permeable pavement and planted several rain gardens with varying vegetation for the study.

Existing concrete from the nearly 300,000-square-foot parking area was removed and crushed. The surface was graded, reusing the crushed concrete as a sub-base material. Three types of permeable pavement surfaces were installed, including 28 of interlocking concrete paver blocks, 41 of porous concrete, and 28 of porous asphalt. Thirteen conventional asphalt spaces were also installed to serve as an experimental control.

Underdrains were installed below each type of paving surface, allowing for testing of each material’s performance in achieving ground water recharge and pollutant removal.

A portion of the infiltrating stormwater is being collected below the surface and piped to below-grade tanks for collection, measurement, sampling, and testing. Stormwater runoff from the conventional asphalt spaces will drain into a new six-cell rain garden where ORD intends to research rain garden sizing.

The goal is to demonstrate and document the performance at reducing stormwater runoff of the three permeable pavement systems – porous asphalt, porous concrete, and interlocking paver blocks – at the same site.

Over the next decade, EPA will evaluate the effectiveness of each pavement type and the rain gardens in removing pollutants from stormwater, and how they help water filter back into the ground.

The parking lot, which is used by the facility’s 462 employees, will be functional during the study to accurately evaluate how the different types of pavement handle traffic and vehicle-related pollution like leaking oil.

The Edison Complex supports the activities of many EPA organizations, including the Office of Solid Waste and Emergency Response’s Environmental Response Branch, the Office of Research and Development’s Release Control Branch, the Regional Environmental Science and Assessment Division, the Regional Enforcement and Compliance Assistance Division’s Pesticides and Toxic Substances Programs, and the Regional Emergency and Remedial Response Division’s Emergency Preparedness Programs.

This parking lot study is part of an effort by EPA’s National Risk Management Research Laboratory to evaluate permeable pavement as it relates to stormwater management practices on a national scale.

While the installation of permeable pavement systems has become more prevalent, there is a lack of full-scale, outdoor, real-world permeable pavement research projects, said Pavlou.

EPA also recognizes the potential of rain gardens as a green infrastructure management tool to lessen the effects of peak flows on waterways.

While local governments and homeowners are building many of these systems, relatively few studies have quantified the ability of rain gardens to allow the ground to better absorb and filter stormwater, which reduces peak flows.